Fuze having a pneumatic and inertia arming system

ABSTRACT

A fuze for a pyrotechnic device having a firing pin for detonating a primer. An inertia sleeve is provided for preventing forward movement of the firing pin until a pneumatic latch is operated by the pressure supplied by a launching force. A borerider pin is also provided for preventing detonation of the primer while the fuze is inside a launcher barrel.

United States Patent 1191 eatty et al. I

1 51 Apr. 3, 1973 [54] FUZE HAVING A PNEUMATIC AND INERTIA ARMING SYSTEM[75] Inventors: Bobby D. Beatty, Bloomfield; Gary' D. Butts, Loogootee;Stanley J. Herold, -Switz City; Donald E. LaGrange, Washington, all ofind.

[73] Assignee: The United States oi America as represented by theSecretary of the Navy 22 Filed: Sept. 20, 1971 21 Appl.No.: 181,791

521 u.s.c1 ..1o2/s1,102/7s [51] Int. Cl. ..F42c 5/00 [58] Field ofSearch .ll02/8l, 76, 78, 7O

[56] References Cited UNITED STATES PATENTS 3,048,111 8/1962 Baker etal. ..l02/8l X 9/1901 Lynch et al ..1o2/s1 2,469,352 5/1949 Lauritsen..l02/8l 2,872,869 2/1959 Rasmussen ..1o2/s1 2,981,192 4/1961 Grandy.....102/7s 3,583520 6/1971 Gawlick ..102/81 Primary Ekaminer samuel W.Engle Attorney-R. S. Sciascia et al.

[57] ABSTRACT A fuze for a pyrotechnic device having a firing pin fordetonating a primer. An inertia sleeve is provided for preventingforward movement of the firing pin until a pneumatic latch is operatedby the pressure supplied by a launching force. A borerider pin is alsoprovided for preventing detonation of the primer while the fuze isinside a launcher barrel.

2 Claims, 6 Drawing Figures PATENTEUAPREJ ms 3, 724. 385

SHEET 1 [1F 2 Fig. 2

21 up 9 Z5 4 5a 435% 5! Y5 Fig. 3

FUZE HAVING A PNEUMATIC AND INERTIA ARMING SYSTEM STATEMENT OFGOVERNMENT INTEREST The invention described herein. may be manufacturedand used by-or for the Government of the United States of America forgovernmental purposes without the payment of any royalties thereon ortherefor.

BACKGROUND OF THE INVENTION The present invention relates to a fuze fora pyrotechnic device, such as a flare, and more particularly relates toa fuze having safety features to prevent accidental arming of the fuze.

Various safety devices are employed to prevent accidental arming andpremature ignition of ordnance devices, as ignition of flares, orexplosion of bombs or missiles, while aboard a ship or plane, creates ahighly dangerous condition. Frequently, an arming' pin, or wire, isprovided to prevent actuation of a firing pin until the arming pin isremoved. For example; in U.S. Pat. No. 3,316,841, which issued May 2,1967, to Charles E. McFann and Arnold S. Munach, there is shown a bombfuze having an arming pin passing through a housing and shaft therebylocking all mova- I ble elements of the fuze until the arming pin isremoved.

Another device for arming a fuze uses a setback slide mechanism whichresponds to setback forces developed during acceleration to arm thefuze. Such a device is shown in U.S. Pat. No. 3,339,488, which issuedSept. 5, 1967, to Julius Borchers. In this patented device, movement ofa setback slide pivots a lever and initiates a timing mechanism torelease a detonator carrier which moves into an armed position.

SUMMARY OF THE INVENTION The present invention relates to a fuze that isto be attached to an ordnance item, such as a pyrotechnic flare, andwhich is to be launched through a launching barrel. A setback slide isprovided which carries a spring-loaded firing pin and forward movementof the setback slide and firing pin is prevented by a borerider pin. Aftmovement of the setback slide is prevented by a locking mechanism whichis unlocked by the pressure applied for launching the ordnance item. Inthe event that the setback slide is unlocked and moves rearward,

if the ordnance item does not clear the barrel, the borerider pin isprovided with means for preventing actuation of the firing pin.

BRIEF DESCRIPTION OF THE DRAWING DESCRIPTION OF THE PREFERRED EMBODIMENTtion 11 is comprised of a housing 13 having a bore 14 in the aft end 'inwhich a pneumatic button 15 is slidably mounted. A shaft 1 6 is attachedto the inner end of pneumatic button 15 and shaft 16 passes through abore 17 in wall 18 of housing 13. A compression spring 19 is providedaround shaft 16 between wall 18 and button 14, and a retaining ring 21is provided on the end of shaft 16 to retain button 15 within housing13. Button 15. is provided with two annular grooves 22 and 23. A sealingring 24 is positioned in groove 22 and groove 23 is arranged to'receivea ball 25 that is positioned in a hole 26 that communicates between bore14 and a second bore 27 in housing 13.

A cylindrical setback slide 28 is positioned in bore 27 and setbackslide 28 is provided with a reduced diameter portion 29 that joins theenlarged diameter portion of slide 28 by a tapered surface 31. A spring32 is provided between one end of setback slide 28 and the end of bore27 to bias setback slide 28 in a forward direction. A bore 33 isprovided in setback slide 28 and a firing pin 34 is slidably positionedin bore 33 of setback slide 28. A ball 35 is provided for locking firingpin 34 in a cocked position and a spring is provided for driving firingpin 34 when firing pin 34 is released. Ball is positioned in a taperedhole 36 in setback slide 28 and the diameter of ball 35 is sufficientlylarge to extend into bore 27 of setback slide 28 and prevent forwardmovement of firing pin 34. A hole 37 is provided in housing 13 toreceive ball 35 when setback slide 28 moves forward to permit release offiring pin 34.

A borerider pin 38 is provided in hole 39 of housing 13 and boreriderpin 38 has a pair of enlarged diameter portions 41 and 42 and ahemispherical portion 43. A

a spring is positioned in hole 39 for biasing borerider pin 38 outwardlyfrom hole 39. As best shown in FIGS. 2 and 6 of the drawings, setbackslide 28 has a slot 44 which is sufficiently large to accept pin 38 butprevents the passage of enlarged diameter portions 41 and 42. A fuze cap45 is threadedly attached to housing 13 and contains a primer 46, delaypellet 47 and ignition pellet 48. As one method of launching the fuzeand attached ordnance item is by compressed air, a sealing ring 49 ofresilient material is provided around the outer periphery of housing 13in an annular groove 51 to prevent excessive leakage of air between theouter perimeter of fuze section 1 1 and the inner surface of a launchingtube 52.

OPERATION Upon launching fu'ze section 11 and the associated ordnanceitem, the propelling force, such as that created by an explosion, orsuch as compressed air, moves pneumatic button 15 against the force ofspring 19 and groove 23 becomes aligned with hole 26 in housing 13. Ball25 is now free to move partially into groove 23 so that setback slide 28will no longer be in a locked condition. As fuze section 11 isaccelerated through launching tube 52, the inertia of setback slide 28causes spring 32 to be compressed and setback slide 28 moves rearwardlyto release borerider pin 38, as shown in FIG. 3 of the drawings. Firingpin 34, however, remains locked with setback slide 28. Spring 40 movesborerider pin 38 so that hemispherical portion 43 contacts launchingtube 52 Referring now to FIG. 4 of the drawings, a malfunction conditionis shown wherein fuze section 11 has not cleared launching tube 52, butis no longer in motion. Spring 32 will drive setback slide 28 to itsoriginal position against borerider pin 38 and firing pin 34 remains ina locked condition by ball 35. In the event that fuze section 11 isremoved manually from launching tube 52, the enlarged diameter 42 ofborerider pin 38 prevents spring 40 from driving borerider pin 38 out ofhole 39.

Referring now to FIG. 5 of the drawings, fuze section 11 has clearedlaunching tube 52 and spring 40 has driven borerider pin 38 out of hole39. After the setback force created by the acceleration of the devicehas diminished, spring 32 drives setback slide 28 forward, as boreriderpin 38 is not now present to prevent movement. When tapered hole 36 insetback slide 28 becomes aligned with hole 37 in housing 13, ball 35moves partially into hole 37 and firing pin 34 becomes unlocked. Firingpin spring 30 then drives firing pin 34 into primer 46 and thedetonation of primer 46 ignites delay pellet 47 which, in turn, ignitesignition pellet 48.

It can thus be seen that two sequential events must take place beforeprimer 46 is detonated by firing pin 34. First, pneumatic button 15 mustbe depressed to release ball 25 and, while button 15 is in thisposition, setback slide 28 must move in an opposite direction to themovement of button 15, in order to release borerider pin 38. Forexample, an accidental dropping of the fuze will not release firing pin34, as two forces acting in opposite directions are required for thisactuation.

We claim:

1. A fuze for a pyrotechnic device compri g,

a housing having first and second longitudinally extending parallelbores,

a setback slide slidably positioned in said first longitudinallyextending bore, said setback slide having a reduced diameter portion,

a pneumatic button slidably positioned in said second longitudinallyextending bore, said pneumatic button having an annular groove in itsperiphery,

a firing pin slidably mounted within said setback slide,

spring means for actuating said firing pin,

releasable means for locking said firing pin in said setback slide,

a borerider pin releasably connected to said setback slide and havingmeans for preventing actuation of said firing pin,

a primer ignitable by said firing pin, and

a locking ball in said housing engageable with said reduced diameterportion of said setback slide for locking said setback slide in saidhousing, said locking ball being receivable in said annular groove ofsaid pneumatic button for unlocking said setback slide whereby saidfiring pin is actuated upon forward movement of said dpneumaticbutton,then rearward movement of sat setback slide, followed by forwardmovement of said setback slide.

2; A fuze for a pyrotechnic device as set forth in claim 1 wherein saidreleasable means for locking said firing pin in said setback slidecomprises a second locking ball engageable with the forward end of saidfiring pin, and a hole in said housing for receiving a portion of saidsecond locking ball thereby unlocking said firing pin.

1. A fuze for a pyrotechnic device comprising, a housing having firstand second longitudinally extending parallel bores, a setback slideslidably positioned in said first longitudinally extending bore, saidsetback slide having a reduced diameter portion, a pneumatic buttonslidably positioned in said second longitudinally extending bore, saidpneumatic button having an annular groove in its periphery, a firing pinslidably mounted within said setback slide, spring means for actuatingsaid firing pin, releasable means for locking said firing pin in saidsetback slide, a borerider pin releasably connected to said setbackslide and having means for preventing actuation of said firing pin, aprimer ignitable by said firing pin, and a locking ball in said housingengageable with said reduced diameter portion of said setback slide forlocking said setback slide in said housing, said locking ball beingreceivable in said annular groove of said pneumatic button for unlockingsaid setback slide whereby said firing pin is actuated upon forwardmovement of said pneumatic button, then rearward movement of saidsetback slide, followed by forward movement of said setback slide.
 2. Afuze for a pyrotechnic device as set forth in claim 1 wherein saidreleasable means for locking said firing pin in said setback slidecomprises a second locking ball engageable with the forward end of saidfiring pin, and a hole in said housing for receiving a portion of saidsecond locking ball thereby unlocking said firing pin.